Dwayne Harris takes up one line on the Giants roster. But the way he figures it, he occupies much more space than that.

“I take up five roster spots that we can use for other things,’’ the affable former Cowboy told The Post on Wednesday. “And I’m probably one of the best at what I do.’’

How can Harris help the Giants? Let us count the ways.

• He is their No. 1 kickoff return man.

• He is their No. 1 punt returner.

• He is their primary gunner on the punt coverage team.

• He is their “L2” man on kickoff coverage, responsible for sprinting to the ball-carrier to make the tackle using an outside-to-inside attack.

• He is a reserve receiver who, if used on offense, instantly would become the Giants’ best blocker down the field.

Of all the important players added by the Giants in the wake of their 6-10 season, Harris, 27, caused few ripples and several furrowed brows. In four years and 52 games, Harris caught 33 passes for the Cowboys, qualifying him as an afterthought on offense.

“A lot of people questioned why they paid me so much,’’ Harris said bluntly. “A lot of people don’t think I did enough to deserve it. My numbers speak for themselves and what I do on the field speaks for itself.’’

If Harris provides for the Giants what he did for the Cowboys, he will be more than worth his salary. In 2013, the Cowboys, based on certain metrics, were fourth in the NFL in total special teams performance; the Giants were 28th. In 2014, the Cowboys were 13th; the Giants 25th. Year after year, the Cowboys excelled while the Giants searched. Now the Giants’ gain is the Cowboys’ loss.

“Powerful, nifty, tough, do a lot of things for you,’’ Tom Coughlin said of Harris.

He can do a lot of things, and also this: He can give the Giants, finally, an identity on special teams, someone to rally around.

“I think he certainly could,’’ Coughlin said. “As one of some guys that are obvious special-teamers, you take great pride in that. Yes, he could.’’

The word after Harris signed is that the Giants promised he would play a larger role as a receiver than he did with the Cowboys. That is partially true. The Giants stressed they would give Harris an opportunity on offense, but this was no deal-breaker.

Dwayne Harris, primarily known as a special teams ace, also could get some playing time at wide receiver.AP

“The thing we talked about was me getting some playing time as a receiver,’’ Harris said. “That was the talk we had. I told Coach, ‘If you need me, I’m here.’ I know we got players, we got Odell [Beckham Jr.], we got [Reuben] Randle, we got Victor [Cruz], we got Preston [Parker], we got Corey [Washington]. We got players who can make plays on offense so we’re not struggling at receiver. Special teams is what they brought me here to do.’’

Harris, though, might thrust himself into the conversation at receiver if he does more of what he did in Wednesday’s practice, beating the defense to haul in a deep ball from Eli Manning.

No one is worried Harris will have much, or any, idle time. He has averaged 11.1 yards on punt returns, 26.5 yards on kickoffs, was the Cowboys’ best gunner and led them in special teams tackles last season with 18. He is described as “explosive’’ and that is not exclusively with the ball in his hands.

“Of the four things I do, I’m pretty sure I’m the best, if you had to pick one guy out who does all the things I do,’’ Harris said. “I’m productive in everything I do. Numbers don’t lie.’’

In past years, Harris took a look, from across the NFC East, at the Giants’ special teams units and saw “a lot of missing parts, but overall it was pretty good. They just need a guy to spark the teams. They just had a couple of things they had to tweak and get fixed, get right.’’

And now Harris is one of them.

“I’m that guy trying to be the tweak,’’ he said. “I’m not the only piece to this puzzle.’’